The invention relates to buffers which are used to detect transitions in the power-consumption mode of an electronic device.
Some electronic memory and processor devices have a low-power consumption or xe2x80x9csleepxe2x80x9d mode in which a circuit within an electronic device temporarily shuts down during relatively long periods of unuse. Buffers are used to detect when it is necessary to xe2x80x9cwake upxe2x80x9d and restore power to the device. These buffers tend to be fast buffers with a symmetrical response because such buffers are advantageously used in other parts of a memory and/or processor device where high speed symmetrical switching is required. However, such symmetry is not always necessary during the condition when power is restored to a circuit, because a restore-power event is relatively rare and is not timing-critical. Additionally, fast buffers with symmetrical response tend to be complex and consume large amounts of power. Accordingly, use of such a buffer to detect a xe2x80x9cwake upxe2x80x9d condition tends to consume a large amount of power when the device is in the sleep mode.
In one aspect, the invention provides a less complex and lower power buffer for detecting a xe2x80x9cwake upxe2x80x9d condition and which enables a plurality of high current buffers which are respectively connected to a plurality of signal lines. The high current buffers are disabled when in a sleep mode and are enabled by the low power buffer detecting the xe2x80x9cwake upxe2x80x9d condition.
In another aspect, the invention provides a method of determining when an electronic device should be enabled in a xe2x80x9cwake-upxe2x80x9d condition, including the steps of monitoring a line which indicates a wake-up condition with a low-power buffer; and enabling a plurality of high-current buffers when a wake-up condition is detected.
In yet another aspect, the invention provides a structure and method which uses a combination of a higher power high current buffer for detecting when a sleep mode is entered, and a lower power buffer for detecting a wake-up condition. The buffer combination is used to disable and enable a plurality of high current buffers.